Head size for a 598" engine...
 

Requirements:
Marine application
Naturally aspirated
Approx. 9.5-9.8 comp ratio
Single carb
Hydraulic roller cam
Power band must be good from 3000-5600rpm

I keep getting 101 different opinions as to what heads would be good enough for a 598" engine and I am sure I will get more by asking here. I would kinda like to see where the majority sits on this idea. I not looking to see how much torque I can make with a 598 incher, therefore I don't really need torque that rips your head off.
The torque that I have now with my 540's is enough. I don't really need more than what I already have, although I realize it may be somewhat unavoidable with a 598.

My 540's now make:

RPM Ft. Pounds of Torque:
3000 592
3500 598
4000 662
4500 694
5000 688
5500 651

I've been told I can run heads 320cc, 335cc, or 360cc. I'm sure they would ALL work okay, BUT I need only as about as much throttle response as what I already have. I know I will already bennefit from the BIGGER cubes from a 598 alone.

With the info I have given; any of you guys want to take a stab at it?

Thanks,
Mark

Dart 355 Pro 1's in case you missed it in the other post.

Only my opinion but I would think a very efficient 320 to 340 CC intake runner will give you very good throttle response and still flow plenty of air to support a 600" motor at 5600 RPM. If you were running solid rollers and planned on twisting 6000 to 6500 RPM 340 to 360 would probably work better.:cool:

Here is a way to look at it. You have 310 CC heads on your 540. Assuming about the same volumetric efficiency and similar RPM you can increase runner volume proportional to engine displacement for equal intake velocity.

540/310 = 598/x

X = 343.3 CC's

Probably not perfect, but better than shooting from the hip. If the baseline of your current 540 is performing the way you want it to it is probably a decent estimate.;)

Kaama,

I'm going to be using using the Dart Pro 1 355's on my 598. But I'll be using a Stage 4 Pro Charger also.

If you're not looking for every ounce you can get the 335's on a nat asp will work just fine.

DAVE

I think I remember that someone used a pair of Dart 360cc heads on a pair of 572 cubic inch engines that only had 8.6 comp ratio, hydraulic roller cam, single dominator and still made more torque/horsepower than my 540's @5200rpm! Perhaps the Dart Pro-1 CNC 355cc, Brodix CNC 355cc 2-Xtra, AFR CNC 357cc, Pro Topline 360 (CNC not available) heads might be the choice. All are within 355cc to 360cc. Perhaps these might be the size heads that will suit what I need. Thanks for all your input and all are guys I highly respect. Anyone else please feel free to chime in and/or add to anything said. Any/all input is appreciated! Thanks.

Mark/KAAMA

BTW, the reason why I don't need/want too much of a torquey engine is to be easier on the Bravo One drives if that is possible.

Mark your bored already????Its going to be a long winter.....leave things alone run it until it breaks then go bigger!!!

YES MARK ,PLEASE AT LEAST GET WHAT YOU'VE GOT TUNED UP AND RUNNING

YOU KNOW IF YOU ASK TEN PEOPLE YOU'LL GET 10 DIFFERENT ANSWERS !!!
THAT QUESTION WAS A BIG ,

DAVE BE CAREFUL WITH DECK THICKNESS ON PRO-ONES WITH A BLOWER ,THE BRODIX AND AIR FLOW RE. HEADS ALL ARE ABOUT
750 THICK ,IT REALLY HELPS

I got a call tonight from AFR telling me they were sending my heads out & I should have next friday. Once I get them I will take & have flowed. Will keep you informed of progress.